IUCN threat status:

Brief Summary

Brief Summary

Posidonia oceanica, commonly known as Neptune Grass or Mediterranean tapeweed, is a marine flowering plant endemic to the Mediterranean Sea. Like other seagrasses, it forms large underwater meadows in the submerged photic zone of sheltered coastal waters (Pirog 2011). Due to its high rate of primary production and its ability to structure and stabilize the seabed, Neptune grass creates habitat for many other marine organisms and thus plays a significant role in littoral Mediterranean ecosystems (Gobert et al. 2006, Kendrick et al. 2005, Pergent et al. 1994).

Posidonia oceanica is one of the largest, slowest growing, and longest-lived plants. In a recent genetic study of 40 P. oceanica populations across the Mediterranean, Arnaud-Haond et al. (2012) found individual clones spanning up to 15 km (9.3 miles). Based on the plant's known growth rate, such individuals are likely to be thousands, possibly tens of thousands of years old (Arnaud-Haond et al. 2012) .